1. Field of the Invention
The present invention relates to a device and a method for drying a synthetic resin pellet that dry and remove water attached to and bound water contained in a synthetic pellet (hereinafter referred to as a resin pellet) that is a molding raw material of a resin molding machine.
2. Description of the Related Art
With respect to a resin pellet dryer that dries and removes water attached to and bound water contained in a surface of a resin pellet supplied as a molding raw material to a resin molding machine, there is one described, for example, in Patent Document 1 (Jpn. Pat. Appln. Laid-Open Publication No. 2005-238691) The disclosed technique includes a pellet containing member, a screw feeder, a vacuum drawing means, a heater, an opening and closing section on an introduction side, an opening and closing section on a discharge side, three operation control sections, and a controller. The pellet containing member is formed by a tube that is disposed in a horizontal state. The screw feeder is disposed in the tube that forms the pellet containing member, and rotationally driven by an electric motor. The vacuum drawing means keeps the inside of the pellet containing member to be in a predetermined vacuum pressure state. The heater is provided in the tube, and keeps the inside of the pellet containing member at a predetermined temperature. The opening and closing section on an introduction side is provided in a pellet introduction section formed on a first end section side of the tube, and driven by a predetermined actuator. The opening and closing section on a discharge side is provided in a pellet discharge section formed on a second end section side of the tube, and driven by a predetermined actuator. The three of the operation control sections control the actuator, the electric motor, and the vacuum drawing means, respectively. The controller carries out temperature control of the heater.
In a resin pellet dryer of the above kind, the water and the bound water are dried and removed in a manner that a required amount of resin pellets are put at once into the pellet containing member having capacity corresponding to an amount of resin pellets consumed by the resin molding machine, and then the inside of the pellet containing member is heated while being evacuated. For this reason, the resin pellet drying device that is used for the resin molding machine that molds a resin molded product of large size needs the pellet containing member of large capacity that contains a large amount of resin pellets. Accordingly, size of the drier itself becomes large and drying time becomes longer, and there is a problem that an enough amount of resin pellets cannot be dried in accordance with an amount of resin pellets consumed by the resin molding machine.
In addition, when a molded product to be molded is changed, a type of resin pellets to be dried needs to be changed. Then, when the resin pellets to be dried are changed, remaining pellets before the change that are attached to the inside of the pellet containing member, the screw feeder, and the like need to be completely removed in order to avoid the resin pellets before the change mixing with those after the change. In order to remove the remaining resin pellets, the remaining resin pellets attached to the pellet containing member and the screw feeder need to be removed after an end section of the pellet containing member is opened and the screw feeder in the inside is taken out. This work is troublesome and changeover time takes long time, and there is a problem that a molding efficiency is lowered.
A problem to be solved is that a long period of time is required for drying a large amount of undried resin pellets at once, a consumption amount of resin pellets of the resin molding machine and a drying amount do not match with each other, and resin molding work cannot be carried out efficiently. Also, there is a problem to be solved that, when changeover of a molded product is carried out, a large amount of work and a long period of time are required for completely removing remaining resin pellets attached to a variety of members that constitute the drier of resin pellets, and the changeover work cannot be carried out efficiently.